Influenza A virus (H1N1) pdm09 hemagglutinin (HA) (HA)

Influenza A virus (H1N1) pdm09 hemagglutinin (HA) is the primary surface glycoprotein of the 2009 pandemic H1N1 influenza virus, which has since become a dominant seasonal strain (1.2.1, 1.5.1). It is a class I fusion protein that exists as a homotrimer on the viral envelope and is essential for viral entry into host cells (1.1.3). The HA1 subunit mediates viral attachment by binding to sialic acid receptors on the respiratory epithelium, while the HA2 subunit facilitates the fusion of the viral envelope with the endosomal membrane under acidic conditions (1.1.2, 1.1.3). As the principal target of the host's neutralizing antibody response, HA is the primary component of seasonal and pandemic influenza vaccines (1.4.1, 1.4.2). Therapeutic strategies targeting HA include small-molecule fusion inhibitors like umifenovir and broadly neutralizing monoclonal antibodies that target the conserved stalk region (1.3.2, 1.3.3). Continuous surveillance of HA mutations is necessary to monitor antigenic drift, which can lead to vaccine mismatch and reduced therapeutic efficacy (1.2.1, 1.4.2).

Other names

H1N1pdm09 hemagglutinin2009 pandemic H1N1 HASwine flu hemagglutininA(H1N1)pdm09 HAApdm09 HAHemagglutinin (HA)

Inhibition of viral attachment to host cell receptors and blockade of pH-dependent membrane fusion.